l18 air pollution i - seoul national university · 2018. 4. 20. · 5 consider a pollutant “i”...
TRANSCRIPT
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• Units for measuring air pollutants• Types of air pollution problems• Types of air pollutants
– Carbon monoxide (CO)– Lead (Pb)– Nitrogen oxides– Photochemical oxidants– Sulfur oxides– Particulates– Other hazardous compounds
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• volume/volume units (for gas phase pollutants)– ppm = parts per million– ppb = parts per billion– ppt = parts per trillion
• mass/volume (for gas & particle phase pollutants)– usually μg/m3
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Consider a pollutant “i”Ideal gas law:
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So,
R = ideal gas constant = 8.21 x 10‐5 m3‐atm/K‐mole
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Q: Convert 10 ppb of SO2 to μg/m3 at 20°C, 1 atm.
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• Classification of air pollution problems by scales–Microscale: less than the size of a house or slightly bigger
–Mesoscale: a few hectares to the size of a city or slightly bigger
–Macroscale: size of a county to a country and to the globe
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• Indoor air pollution: pollutants from burners, ovens, heaters, cigarette smoke, and underground
• Cigarette smoke on streets
http://www.compacappliance.net http://www.odamindia.org http://www.edaily.co.kr
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• Vehicle exhaust• Smoke from power plants, factories, etc.• Smog
http://www.bbc.comhttp://web.ornl.gov
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• Acid rain• Yellow dust• Ozone depletion• Global warming http://en.wikipedia.com
http://breitbart.com
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• Generated by incomplete combustion of carbon • Natural sources: oxidation of methane (CH4) in the atmosphere
• Anthropogenic sources: motor vehicles, fossil fuel burning, solid waste disposal, burning of plant materials
• Reacts with hemoglobin in the blood to form carboxyhemoglobin (CoHb)
• Carbon monoxide poisoning: lots of deaths in 1950s‐1980s in Korea caused by indoor briquette burning
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• A cumulative poison• Usually occurs in the atmosphere as a particulate• Natural sources: volcanic activity and airborne soil• Anthropogenic sources: smelters and refining processes, and incineration of lead‐containing wastes
• In the past, lead used to be added to gasoline significant air pollution problems lead addition currently prohibited
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• NO, NO2, N2O, NO3, N2O3, N2O4, N2O5
• NO2 itself has adverse effects on respiratory tract• NO and NO2 are involved in the formation of photochemical smog and acid rain
• NOx = NO + NO2
• Anthropogenic sources: combustion processes in motor vehicles, power plants, and the industry
• N2 is an inert gas, but reacts with oxygen at high temperature (>1600 K):
N2 + O2 2NO
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• Chemicals produced by reaction in the atmosphere in the presence of sunlight
• Classified as secondary pollutants • O3 (major), peroxyacetyl nitrate (PAN), acrolein,
peroxybenzoyl nitrates (PBzN), aldehydes, nitrogen oxides
• Toxic effects because of their oxidizing ability: cause eye, nose, and throat irritation, and affect lung function
• Major pollutants in photochemical smog
ozone PAN
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• Primary pollutants– Pollutants that are emitted directly from sources
• Secondary pollutants– Pollutants that are formed in the atmosphere by chemical reactions between primary pollutants and chemical species normally found in the atmosphere
Ozone
PAN
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• SO2, SO3, SO42‐
• Called SOx
• Sources– Direct emission of SOx from power plants, industry, volcanoes, and the oceans (as a primary pollutant)
– Oxidation of H2S produced by natural biological processes or the industry (as a secondary pollutant)
• Involved in “London‐type smog” and acid rain
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• Particles suspended in the air• Natural sources: sea salt, soil dust, volcanic particles, smoke from forest fires
• Anthropogenic sources: fossil fuel burning, industrial processes
• Damage respiratory organs
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• Large particles are trapped at the upper respiratory system, but small particles go deeper small particles are more significant!
• Korean government regulate “PM10” and “PM2.5”– PM10: particulate matter less than 10 μm size– PM2.5: particulate matter less than 2.5 μm size
Deposition of inhaled particles in the humanRaabe (1994) Internal Radiation Dosimetry
(기관지)
(코, 입)
(폐)
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• Toxic organic compounds, heavy metals, arsenic, etc.• Korean government regulates 35 hazardous air pollutants
• Some examples: cadmium, mercury, asbestos, dioxin, benzene
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Textbook Ch 12 p. 580‐600
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Slide#6 solution)10 ppb = 0.01 ppmMW of SO2 = 64.1SO2 conc. in μg/m3
0.01 64.1 / . /
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